NECT Gr 10 Heating and Cooling Curve of Water

Summary

In this educational video, hosts John McBride and Joyce Polka conduct an experiment to measure the temperature changes of water as it melts and boils, and as it cools down. They use a thermometer, ice, and a Bunsen burner to record temperatures at one-minute intervals. The experiment aims to plot heating and cooling curves of water, illustrating the phase changes and temperature fluctuations over time. The video guides viewers through setting up the apparatus, identifying variables, and recording data, concluding with a demonstration of how to plot the results.

Takeaways

• 🔬 The experiment involves measuring the temperature of water as ice melts and is heated to boiling, and as hot water cools down.
• 📈 The goal is to plot heating and cooling curves of water, which show temperature changes over time.
• ⏱️ Temperature is measured every minute during the experiment to record changes in the water's state.
• ❄️ The initial setup includes crushed ice, a thermometer, a heat source (Bunsen burner), and a beaker to contain the ice and water.
• 🌡️ An alcohol thermometer is used, and readings are taken from the bottom of the meniscus.
• 🔥 The Bunsen burner is used to heat the ice and water mixture, with a gozman to distribute heat evenly.
• 🕒 The independent variable is the time interval between temperature recordings, set at one minute.
• 💧 The dependent variables are the temperature of the water and its phase (solid, liquid, or both).
• 🔍 Control variables include maintaining a constant Bunsen burner flame and ensuring the mass of water remains constant throughout the experiment.
• 📊 Data collected will be used to plot graphs, with careful attention to accuracy and decimal places for consistency.

Q & A

What is the purpose of the experiment described in the script?

The purpose of the experiment is to measure the temperature of water as it melts and is heated to its boiling point, and also as it cools, to plot heating and cooling curves of water.

What are the two types of graphs that will be plotted based on the experiment?

The two types of graphs that will be plotted are the heating curve of water and the cooling curve of water.

What is the initial temperature of the crushed ice mentioned in the script?

The initial temperature of the crushed ice is zero degrees Celsius.

What is the role of the Bunsen burner in the experiment?

The Bunsen burner is used as a heat source to heat the ice and water, allowing the temperature to rise and the ice to melt.

Why is it important to pack ice around the thermometer?

Packing ice around the thermometer ensures that the temperature measured is that of the ice and not the surrounding air.

What is the significance of the time interval chosen for recording temperatures?

The time interval between temperature recordings is the independent variable in this experiment, and it affects the dependent variable, which is the temperature of the water.

What is the dependent variable in the context of this experiment?

The dependent variable is the temperature of the water, which changes based on the amount of heat supplied by the Bunsen burner and the time the water is heated.

Why is the phase of water also considered a dependent variable in this experiment?

The phase of water is considered a dependent variable because it changes when the ice is heated above zero degrees Celsius, indicating a transition from solid to liquid.

What are the control variables in this experiment, and why are they important?

The control variables include the constant rate of the Bunsen burner flame, the mass of water, and ensuring no additional water is added or lost during the experiment. These variables are important to ensure consistent and reliable results.

How does the experiment account for the water that evaporates during heating?

The experiment acknowledges the slight loss in mass due to evaporation but does not adjust the mass of the water manually; it is considered a natural part of the heating process.

What is the expected outcome when the ice is heated at a constant rate?

When ice is heated at a constant rate, the expected outcome is a graph showing a constant temperature until the ice melts, followed by a steady rise in temperature as water is heated towards its boiling point.